Conveyor mechanism using an electro-pneumatic roll lift mechanism

ABSTRACT

A conveyor mechanism feeds stock material into a material working station. The conveyor mechanism includes a frame, a feed roll, a pinch roll, a pinch roll lift mechanism, and a height monitoring device. The feed roll has a feed roll axis, the feed roll axis being rotatably fixed relative to the frame. The pinch roll opposes the feed roll and is selectively moveable relative thereto. The pinch roll has a roll lift position relative to the feed roll. The pinch roll lift mechanism is configured for selectively controlling the roll lift position of the pinch roll. The height monitoring device is configured for monitoring the roll lift position and measuring an actual roll lift height of the pinch roll. The height monitoring device is operatively coupled with the pinch roll lift mechanism in order to permit the actual roll lift height to be used by the pinch roll lift mechanism in selectively controlling the roll lift position.

CROSS REFERENCE TO OTHER APPLICATIONS

This application claims priority to U.S. Provisional Patent application No. 60/511,052 filed Oct. 10, 2004, the disclosure of which is hereby explicitly incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a press feed or conveyor mechanism for feeding sheet and/or strip stock material into a machine, such as a press, and more specifically to a mechanism employing an electro-pneumatic roll lift mechanism.

2. Description of the Related Art

A common way of feeding material to a press is by clamping the stock material between two rolls and rotating those two rolls in a manner that advances the material into the press. To provide this clamping action, one roll is normally fixed for rotation and the second roll is free to move toward and away from the first roll. The fixed roll is often called a feed roll, and the moveable roll is commonly named a pinch roll.

In some press applications, after the required amount of material is fed into the press, it is necessary to unclamp the material so that it can be properly aligned with the guide before the workpiece is formed. This unclamping or separation of the pinch roll from the feed roll is termed roll lift. Roll lift, if not accurate and/or in time, can prohibit alignment of the material, causing damage to the workpiece and/or the die. Furthermore, the pinch roll needs to resume its clamping position in a controlled manner. Slamming of the pinch roll into the material can cause the roll to bounce and/or deform the material.

What is needed in the art is a conveyor system employing a feed roll and a pinch roll that will promote accurate and timely lifting of the feed roll, as well as the controlled return of the pinch roll into its clamping position.

SUMMARY OF THE INVENTION

The present invention relates to a press feed conveyor mechanism used to feed stock material into a press, the conveyor mechanism incorporating an electro-pneumatic means of performing roll lift. The electro-pneumatic roll lift mechanism includes a pneumatic piston/cylinder arrangement with an integrated solenoid valve and is operatively linked to a pinch roll of the conveyor mechanism. The pressure to the piston/cylinder arrangement is controlled by a proportional air pressure controller, which receives feedback from a linear encoder through a programmable logic controller. The linear encoder monitors the position of the pinch roll, and the pressure to the piston/cylinder mechanism is accordingly adjusted based upon the actual position desired.

The present invention, in one form thereof, is a conveyor mechanism for feeding stock material into a material working station. The conveyor mechanism includes a frame, a feed roll, a pinch roll, a pinch roll lift mechanism, and a height monitoring device. The feed roll has a feed roll axis, the feed roll axis being rotatably fixed relative to the frame. The pinch roll opposes the feed roll and is selectively moveable relative thereto. The pinch roll has a roll lift position relative to the feed roll. The pinch roll lift mechanism is configured for selectively controlling the roll lift position of the pinch roll. The height monitoring device is configured for monitoring and measuring an actual roll lift height of the pinch roll. The height monitoring device is operatively coupled with the pinch roll lift mechanism in order to permit the actual roll lift height to be used by the pinch roll lift mechanism in selectively controlling the roll lift position.

An advantage of the present invention is that the roll lift mechanism permits continuous monitoring and adjusting of the roll lift position and/or height, thereby allowing for optimal roll lift performance.

Another advantage of the present invention is that the roll lift mechanism allows for higher cycle rates by facilitating the minimization of unnecessary roll lift height.

Yet another advantage resulting from the minimization of the needed roll lift height is a reduction of slamming of the roll and/or roll bounce.

A further advantage of the present invention is that the system may be operated in an automated manner upon entry of the desired clamp force and roll lift height.

BRIEF DESCRIPTION OF THE DRAWINGS

The above-mentioned and other features and advantages of this invention, and the manner of attaining them, will become more apparent and the invention will be better understood by reference to the following description of an embodiment of the invention taken in conjunction with the accompanying drawings, wherein:

FIG. 1 is a perspective, partial schematic view of the conveyor system of the present invention, employing an electro-pneumatic roll lift mechanism;

FIG. 2 is a schematic view of a sheet material processing system incorporating the conveyor system of FIG. 1; and

FIG. 3 is a side, schematic view of the feed and pinch rolls and the interposed sheet material of FIG. 1, with the pinch roll shown in a open or raised position.

Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates one preferred embodiment of the invention, in one form, and such exemplification is not to be construed as limiting the scope of the invention in any manner.

DETAILED DESCRIPTION OF THE INVENTION

The conveyor mechanism 10 of the present invention, as shown in FIG. 1, is configured for conveying a sheet material 12 in a feed direction F toward a workstation 14 (shown in block format in FIG. 2). Workstation 14, in a preferred embodiment of the present invention, is a machine press, but may, for example, be any station at which the sheet material 12 is one of mechanically worked; thermally treated; chemically cleaned, treated, or etched; and/or otherwise processed. Returning to FIG. 1, conveyor system 10 generally includes a conveyor frame 16, a feed roll 18, a pinch roll 20, and an electro-pneumatic roll lift mechanism 21. Roll lift mechanism 21 further includes a pivotable pinch roll mount system 22, pneumatic piston/cylinder system 24, solenoid valve 42, a first proportional pressure controller (PPC) 26, a second PPC 28, and a controller, such as programmable logic controller (PLC) 30. Conveyor system 10 further includes a roll lift position monitor 32.

The rotation of feed roll 18 in rotational direction R_(F) and the simultaneous rotation of pinch roll 20 in direction R_(P) together causes sheet material 12 to move in feed direction F. Feed roll 18 is pivotably fixed in machine frame 16 (the frame 16 being shown in phantom, proximate feed roll 18). Meanwhile, pinch roll 20 is controllably movable up and down via electro-pneumatic roll lift mechanism 21 and, specifically, by pivotable pinch roll mount system 22.

Pinch roll mount system 22 includes a roll mount linkage 34 and a linkage pivot shaft 36. Pinch roll 20 is pivotably mounted within one end of roll mount linkage 34, while pneumatic piston/cylinder system 24 is operatively coupled to the other end of such linkage 34. Roll mount linkage 34, in turn, is mounted about linkage pivot shaft 36. Linkage pivot shaft 36 is fixably rotatable within frame 16 (shown in phantom adjacent to shaft 36). Due to the combined operations of roll lift mechanism 21 and linkage pivot shaft 36, roll mount linkage 34 is able to selectively raise and lower pinch roll 20 about pivot shaft 36 in a pivotal direction P.

Piston/cylinder system 24 is able to create linear movement along cylinder direction C. An extension of piston/cylinder system 24 (specifically an extension of a cylinder rod (not illustrated) of system 24) along direction C causes linkage 34 to pivot in a manner so as to move pinch roll 20 away from feed roll 18 into an open position. Retraction of piston/cylinder system 24 results in the pinch roll 20 being pivoted or closed toward feed roll 18 via movement of linkage 34. If pivoted close enough together, such action will clamp sheet material 12 between the two rolls 18, 20 for controlled movement based on the controlled rotation of rolls 18, 20 (i.e., stopped or rotating to produce a desired feed speed). As such, piston/cylinder system 24 can be used to accommodate various thicknesses of sheet material 12 between rolls 18, 20 and, more generally can be used to control whether or not pinch roll 20 engages sheet material 12. Additionally, the amount of force applied on sheet material 12 by pinch roll 20 can selectively be adjusted to promote stoppage of material 12 or to optimize roll grip (minimized slip) and feed efficiency combinations.

Piston/cylinder system 24 includes a front (rod) side 38 directed toward roll mount linkage 34 and further includes a rear side 40. Mounted on rear side 40 of piston/cylinder system 24 is a solenoid valve 42. Fluid pressure such as pressurized air is provided to front side 38 of piston/cylinder system 24 which biases the piston/cylinder system to retract and apply a clamp force between rolls 18 and 20. This pressure, as per the present embodiment, is always constant and is controlled by first proportional pressure controller (PPC) 26. The necessary clamping force (the force needed to stop or controllably move sheet 12 using rolls 18, 20) can be set at the control panel (not shown) for conveyor mechanism 10. This inputted clamping force is received by programable logic controller (PLC) 30, which then interprets and sends the appropriate signals to PPC 26. PPC 26 changes the pressure based on the electrical signal it receives. It is to be understood that the function of PLC 30 can be fulfilled by a personal computer (PC) or by another type of machine controller. Such alternatives for PLC 30 are considered to be within the scope of the present invention.

When it is time to open roll 20 away from roll 18, solenoid valve 42 allows air to flow into the rear of piston/cylinder system 24 to cause extension of piston/cylinder system 24 (in particular the cylinder thereof (not shown)) toward roll mount linkage 34 and thereby open rolls 18, 20. The air (or other fluid) pressure provided to rear side 40 of piston/cylinder system 24 must be sufficient enough to overcome the pressure in the front side 38 in order for the cylinder rod of piston/cylinder system 24 to be able to extend. The air pressure to solenoid valve 42 is controlled by second PPC 28. During the roll lift operation described, the operating voltage of the solenoid valve 42 is momentarily increased above its normal operating specification (i.e., a rating of 24 volts). This temporary increase in operating voltage enhances the valve responsiveness and thereby increases the achievable roll lift rates. As a result, the press feed can achieve higher cycle rates and be able to match press speeds.

In an alternative embodiment (not shown), front side 38 of piston/cylinder system 24 could also be provided with a solenoid valve; this provision would permit a variably controlled degree of air pressure to be introduced into the front side of piston/cylinder system 24. Variable control of the pressure would be available at both the front and back side 38, 40 of piston/cylinder system 24, thereby increasing the flexibility for controlling system 24.

Roll lift position monitor 32 is in the form of a linear encoder in the present embodiment, yet it is to be understood that other position monitoring means could instead be employed within the scope of the present invention. Height position monitor/linear encoder 32 detects and measures roll lift height H (FIG. 3), which is measure relative to surfaces positions S of material 12. During each press forming cycle, the set or zero position of pinch roll 20, when the roll is closed and clamping material 12, is equal to surface position S and is encoded by linear encoder 32. Linear encoder 32 relays this set position value to PLC 30.

Pinch roll 20 is then moved so as to be a distance roll lift height H above surface position S. Linear encoder 32 then registers the position which corresponds to that roll lift position (i.e., H+S) and provides the appropriate position signal to PLC 30. (Note that H+S actually also equals the separation distance between roll 18, 20 in the roll lift positions.) PLC 30 interpolates the signal (H_(ACTUAL)=(H+S)−S), compares it to a set roll lifts height value H entered at the control panel of the machine or other data entry means, and sends the appropriate logic control signal to PPC 28. The signal will indicate the degree of adjustment in pressure to be made in PPC 28 to achieve the desired roll lift height H and thereby control the amount of opening between rolls 18, 20, as needed. If an adjustment is needed, PPC 28 will then produce or control a new pressure output based on this signal. This adjustment procedure assures the same amount of roll lift height H each time, regardless of any variances in material thickness. That is, by knowing the linear position at which pinch roll 20 is in contact with material 12, pinch roll 20 need only be moved further upwards by a distance of the desired roll lift height H to be at its desired lift position, no matter the potentially changing thickness of material 12.

PLC 30 and linear encoder 32 form a feedback control system allowing roll lift mechanism 21 to operate as a closed-loop servo feedback configuration. This closed-loop servo feedback configuration permits continuous monitoring and adjusting of the desired roll lift position, either for the clamped or open (roll lift height H) position. Such continuity promotes optimal roll lift performance. By optimizing roll lift performance, various shortcomings can be avoided. Excessive roll lift height (H) increases the amount of time to open or close roll 20 relative to roll 18, resulting in lower cycle rates. Thus, by minimizing unnecessary roll lift heights, higher cycle rates can be obtained. Yet further, minimizing of roll lift height H (to provide the minimum clearance needed for realignment of material 12) also reduces slamming of rolls 18, 20 and/or roll bounce therebetween.

The closed-loop servo feedback configuration of the present invention allows the system to operate in a fully automated manner. Both the clamp force and roll lift height H can be entered at the control panel of the machine. From there, PLC 30 is able to automatically control the operation of conveyor mechanism 10.

While this invention has been described as having a preferred design, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims. 

1. A conveyor mechanism for feeding stock material into a material working station, the stock material having a material surface said conveyor mechanism comprising: a frame; a feed roll having a feed roll axis, said feed roll axis being fixed relative to said frame; a pinch roll opposing said feed roll, said pinch roll being selectively movable relative to said feed roll, said pinch roll having a roll lift position relative to said feed roll; a pinch roll lift mechanism configured for selectively controlling said roll lift position of said pinch roll; and a height monitoring device configured for monitoring said roll lift position and for measuring an actual roll lift height of said pinch roll relative to the material surface, said height monitoring device being operatively coupled with said pinch roll lift mechanism in order to permit said actual roll lift height to be used by said pinch roll lift mechanism in selectively controlling said roll lift position.
 2. The conveyor mechanism of claim 1, wherein said pinch roll lift mechanism includes a closed-loop servo feedback system configured for selectively adjusting said roll lift position said feedback system being configured for forming a height comparison between roll lift height and a set roll lift height, said height comparison serving as a basis for adjusting operation of said pinch roll lift mechanism.
 3. The conveyor mechanism of claim 1, wherein said pinch roll lift mechanism includes a piston-cylinder actuator configured for selectively maneuvering said pinch roll based upon said actual roll lift height measured by said height monitoring device.
 4. The conveyor mechanism of claim 1, wherein said height monitoring device is configured for encoding a pinch roll lift position.
 5. The conveyor mechanism of claim 4, wherein said height monitoring device is comprised of a linear encoder.
 6. The conveyor mechanism of claim 5, wherein said pinch roll lift mechanism includes a controller, said linear encoder being configured to relay said pinch roll lift position to said controller, said controller being any one of a programmable logic controller, a machine controller, and a personal computer.
 7. The conveyor mechanism of claim 1, wherein said pinch roll lift mechanism includes a controller, a pneumatic piston/cylinder mechanism, and at least one proportional pressure controller, said controller being any one of a programmable logic controller, a machine controller, and a personal computer.
 8. The conveyor mechanism of claim 7, wherein said controller generates a logic control signal, said pneumatic piston/cylinder mechanism being operatively connected to said pinch roll, said proportional pressure controller being configured for receiving said logic control signal from said controller, said proportional pressure controller being further configured for selectively pressurizing said pneumatic cylinder based on said logic control signal to thereby adjust said roll lift position of said pinch roll.
 9. A press system, comprising: a mechanical press for mechanically shaping a stock material; and a conveyor mechanism for feeding the stock material into said mechanical press, the stock material having a material surface, said conveyor mechanism comprising: a frame; a feed roll having a feed roll axis, said feed roll axis being fixed relative to said frame; a pinch roll opposing said feed roll, said pinch roll being selectively movable relative to said feed roll, said pinch roll having a roll lift position relative to said feed roll; a pinch roll lift mechanism configured for selectively controlling said roll lift position of said pinch roll; and a height monitoring device configured for monitoring said roll lift position and for measuring an actual roll lift height of said pinch roll relative to the material surface, said height monitoring device being operatively coupled with said pinch roll lift mechanism in order to permit said actual roll lift height to be used by said pinch roll lift mechanism in selectively controlling said roll lift position.
 10. The press system of claim 9, wherein said pinch roll lift mechanism includes a closed-loop servo feedback system configured for selectively adjusting said roll lift position, said feedback system being configured for forming a height comparison between roll lift height and a set roll lift height, said height comparison serving as a basis for adjusting operation of said pinch roll lift mechanism.
 11. The press system of claim 9, wherein said pinch roll lift mechanism includes a piston-cylinder actuator configured for selectively maneuvering said pinch roll based upon said actual roll lift height measured by said height monitoring device.
 12. The press system of claim 9, wherein said height monitoring device is configured for encoding a pinch roll lift position.
 13. The press system of claim 12, wherein said height monitoring device is comprised of a linear encoder.
 14. The press system of claim 9, wherein said pinch roll lift mechanism includes a controller, a pneumatic piston/cylinder mechanism, and at least one proportional pressure controller.
 15. The press system of claim 14, wherein said controller is any one of a programmable logic controller, a machine controller, and a personal computer. 